(HealthDay News) -- All things being equal, an unmarried heart patient may face a higher risk of death than a married heart patient, new research suggests.

After reviewing four years of data on more than 6,000 heart patients, researchers determined that being unmarried seems to bump up the risk of dying not only from cardiovascular illness, but dying for any reason whatsoever.

"Compared to married subjects, being unmarried was associated with a 45 percent higher risk for dying [from heart disease], even after accounting for differences in risk factors, disease severity, medication use and socioeconomic factors," said study co-author Dr. Arshed Quyyumi.

He is a professor of medicine with Emory University School of Medicine's division of cardiology in Atlanta.

Quyyumi noted this is the first study to look at heart disease patients across a wide range of relationship categories, including never married, divorced or separated, and widowed.

That means the team can only offer "potential explanations" for the study's findings. One reason why: the study only found an association between higher death rates and heart patients, not a cause-and-effect connection.

But Quyyumi pointed to a possible lack of social support among single patients, as well as increased stress and depression, and poorer adherence to medication regimens and healthy lifestyle choices, as explanations for the findings.

He and his colleagues reported their findings in the Dec. 20 issue of the Journal of the American Heart Association.

Participating patients were 63 years old, on average, and were all undergoing treatment for heart disease at an Emory health care facility.

About three-quarters were male, and about a quarter were black. A completed survey revealed that among the participants, black women were more likely to be unmarried. It also indicated that unmarried patients were also more likely to struggle with high blood pressure, heart failure and/or high cholesterol.

During the nearly four-year study, slightly more than 1,000 of the patients died.

In the end, the investigators found that being unmarried seemed to increase the risk for dying of any cause by 24 percent, compared with married heart disease patients. They also faced a 52 percent higher risk for dying due to cardiovascular death or heart attack.

Digging deeper, the researchers observed that the risk of dying from cardiovascular death or a heart attack rose roughly 40 percent among those who had never been married and those who had been divorced or separated, compared with their married peers.

The rise in risk was even higher among those who had been widowed, rising by 71 percent compared with patients who were still married. The bump in death risk was particularly notable among patients younger than 65, Quyyumi added.

The findings suggest that marital status might need to be taken into consideration when caring for heart patients, he said.

But Quyyumi cautioned that the study did not explore death risk among unmarried heart patients who were in a relationship and perhaps even living with their partner. And he added that because the study only enlisted patients being cared for at a single medical facility, it may be difficult to draw too many conclusions from the findings.

Dr. Vincent Bufalino, director and senior vice president of Advocate Health Care in Naperville, Ill., was somewhat surprised by the findings.

"And it certainly does give you pause," he said. "And it suggests that there might be something about the life experience of unmarried patients that is different from that of their married peers."

What exactly that is, Bufalino noted, remains to be explored. But he pointed to the increased stress loads that might burden unmarried patients.

"By itself, it's hard to manage your life, your finances, the responsibility of children and parents, whatever the stressors are that might affect folks," said Bufalino, who was not involved with the study.

"When you have a partner, at the very least some of that is diffused and shared. Of course, we still don't really understand the direct connection between stress and cardiovascular disease, Bufalino said. "But the fact that there is an association is clear, and this finding may be another supportive example of that."

Another heart expert agreed.

"To me, this makes sense," said Dr. Sana Al-Khatib, a professor of medicine in Duke University's division of cardiology-electrophysiology. "Having social support may ease up some of the stress that patients with [heart disease] face."

"Also, a spouse may help patients be more attentive to their health, reminding them to take their medications, abide by a healthy lifestyle and diet, and be strong in fighting their disease," Al-Khatib added. "It will be important to see if these results can be replicated by others perhaps in a multi-center study."

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